Xiphophorus cortezi, the delicate swordtail, is a species of poeciliid fish from Mexico.

[2] Named after the Spanish conquistador Hernán Cortés, Xiphophorus cortezi was originally described in 1960 by Donn Eric Rosen as a subspecies of X. montezumae.

The color of the male, especially the midlateral stripe, depends on the excitement of the fish and background shade of its environment.

Some specimens kept in the laboratory for years have shown such silvery coloring that black markings became absent.

[2] Xiphophorus cortezi is found in the upper Rio Panuco system in northeastern Mexico.